In recent years, there has been an increasing number of surgeons using surgical staples, rather than conventional sutures. This is true because the use of surgical staples and surgical stapling instruments has made many difficult procedures much simpler to perform. Of more importance, however, is that the use of surgical staples significantly reduces the time required for most procedures, and therefore reduces the length of time which the patient must be maintained under anesthetic. Many types of surgical stapling instruments have been devised for different surgical procedures.
The present invention is directed to a surgical instrument for applying surgical fasteners to internal organs and tissues such as the lung, esophagus, stomach, duodenum, and intestines. The invention is embodied in a linear surgical stapler which permits access to restricted surgical sites, e.g., the pelvic area of the human body.
In its earliest form, the linear surgical stapling instrument was a permanent, multi-use instrument and the surgical staples were manually loaded into the instrument one at a time. An example of a surgical stapling instrument of this type is disclosed in U.S. Pat. No. 3,080,564. This type of instrument was, in general, complex in construction, expensive to manufacture, heavy, bulky and difficult to both load the surgical staples and to clean and sterilize after each use. A subsequent improvement in linear surgical stapling instruments was the provision of presterilized, disposable loading units or staple cartridges. U.S. Pat. Nos. 3,275,211, 3,315,863 and 3,589,589 disclose examples of permanent, multi-use linear instruments having replaceable staple cartridges.
Several types of surgical fastener applying instruments are known for applying surgical fasteners to body tissue clamped between relatively movable fastener holding and anvil portions of the instrument. The surgical fasteners may be metal staples as shown, for example, in U.S. Pat. No. 3,275,211, or consist of non-metallic resinous materials as shown, for example, in U.S. Pat. No. 4,402,445. In the case of metal staples, the staple legs are typically driven through the tissue and formed by the anvil to secure the staples in the tissue. In the case of non-metallic fasteners, each fastener may initially consist of two separate parts, i.e., a fastener part disposed in the fastener holding part of the apparatus, and a retainer part disposed in the anvil part of the apparatus. The leg or legs of the fastener parts are driven through the tissue and interlock with the retainer parts to secure the fasteners in the tissue. Although most surgical staples are biologically inert and remain permanently in the body, biologically absorbable metal surgical staples are known. Surgical fasteners of non-metallic resinous materials can also be made either biologically absorbable or non-absorbable.
The surgical instrument of the present invention is not limited to use with any particular type or form of fasteners. The various surgical fasteners mentioned above represent examples of the types of fasteners which can be used with the instrument of the present invention. Thus, as used herein, surgical fastener is meant to be generic to all of the above fasteners, including both staples and two-part devices. Similarly, as used herein, fastener holder and anvil are terms which are generic to surgical instruments for applying the above types of fasteners.
In the prior instruments disclosed in U.S. Pat. Nos. 3,275,211 and 4,402,445 for applying surgical fasteners to tissue clamped between the fastener holding and anvil portions of the instrument, a distal fastener applying assembly is rigidly connected to the proximal actuator portion of the instrument. More recently, however, there has been increasing interest in instruments in which the connection between the fastener applying assembly and the actuator assembly is not completely rigid. U.S. Pat. No. 4,473,077, for example, shows a surgical stapler in which the shaft assembly connected between the fastener applying and actuator assemblies is transversely flexible in a single plane.
Also, in view of rising hospital costs, there has been an ever increasing interest in disposable surgical stapling instruments to eliminate as much work as possible, i.e., disassembly, cleaning, reassembly, sterilization and the like, and to be more efficient, while at the same time, not having to compromise the surgical procedures. U.S. Pat. Nos. 4,354,628, 4,383,634 and 4,527,724, for example, each disclose disposable linear surgical stapling instruments.
U.S. Pat. Nos. 4,566,620, 4,728,020 and 4,869,414, disclose other examples of instruments for applying surgical fasteners to tissue clamped between the fastener holding and anvil portions of the instrument. An articulated surgical fastener applying apparatus is disclosed in U.S. Pat. No. 4,566,620 in which the fastener applying assembly is rotatably mounted at the distal end of a longitudinal shaft assembly by a joint for allowing rotation of the fastener applying assembly relative to the actuator assembly about each of three mutually orthogonal axes. U.S. Pat. Nos. 4,728,020 and 4,869,414 each disclose an articulated surgical fastener applying apparatus including a fastener applying assembly mounted at the distal end of a longitudinal shaft assembly for pivotal movement about an axis transverse to the longitudinal axis of the shaft assembly which is substantially inflexible about all other axes parallel to the transverse axis. The shaft assembly is rotatably mounted on a proximal actuator assembly to allow rotation of the fastener applying assembly relative to the actuator assembly about the longitudinal axis of the shaft assembly. One drawback of these instruments is that the access of the fastener applying assembly into the pelvic area is restricted by the relatively large dimensions of the fastener holding portions of the instruments. Also, the fastener applying assembly of these instruments includes protruding latch buttons and alignment pin carriers which further limit the access of the fastener applying assembly into the pelvic area.
Additional examples of surgical instruments including a fastener applying assembly provided with relatively movable fastener holding and anvil portions are disclosed in U.S. Pat. Nos. 4,591,085 and 4,941,623. The instrument disclosed in U.S. Pat. No. 4,591,085 includes a trigger interlocking mechanism which precludes the actuation of the trigger until an appropriate gap is set between the jaws of the instrument.
U.S. Pat. No. 4,938,408 discloses a surgical stapling instrument including a rotatable support shaft on which a stapler head is rotatably mounted for rotation about an axis normal to the axis of the support shaft. U.S. Pat. No. 5,137,198 discloses a linear surgical stapling instrument including a fast jaw closure mechanism and a trigger safety device.
In co-pending U.S. patent application Ser. No. 832,299, filed on Feb. 7, 1992, now U.S. Pat. No. 5,271,543, entitled "Surgical Anastomosis Stapling Instrument With Flexible Support Shaft And Anvil Adjusting Mechanism", assigned to the same assignee as the present invention, a surgical stapling instrument including a flexible shaft assembly is disclosed. The flexible shaft assembly comprises a pair of elongated helical elements which are concentrically wound together with the coils of the first helical element alternately interspersed with the coils of the second helical element. Each coil of the first helical element has a round cross section and each coil of the second helical element has a triangular cross section provided with sloped surfaces which slidably engage the adjacent round coils. There is, however, no disclosure of any mechanism to limit the bending of the flexible shaft assembly.